Pumps – With condition responsive pumped fluid control – Normally open bypass or relief passage closed by increased...
Utility Patent
1999-10-22
2001-01-02
Leung, Philip H. (Department: 3742)
Pumps
With condition responsive pumped fluid control
Normally open bypass or relief passage closed by increased...
Utility Patent
active
06168390
ABSTRACT:
BACKGROUND
1.0. Field of the Invention
This invention relates generally to a feed pump for conveying liquids in dosed amounts, and more particularly to such a feed pump including a mechanism for dearerating the liquid as it is pumped. The pump comprises a suction valve built into an intake line coming from an intake container; a pump chamber behind the suction valve of which the displacement volume can be changed by a pump element; a pressure valve leading to the feed line, a venting device with a nonreturn valve arranged at the upper end of the pump; and a flow-actuated vent and bypass valve which is built into a vent line and of which the response behavior depends on the aggregate state of the fluid bearing against it, this valve being opened in the inoperative position and closed only during the compression stroke when liquid is bearing against the valve and comprising an elastic membrane.
2.0. Discussion of Related Art
In a known such feed pump as described above, the membrane of the vent valve has an opening acting as a flow restrictor with such a diameter that, when gases flow through, the membrane is not deflected, but moves when liquid bears against the membrane during the compression stroke so that the valve outlet is closed. In this way, the liquid in the pump chamber is able to release the gas present in it to the vent line both during the compression stroke and during the suction stroke. When the liquid has been fully deaerated, however, the membrane closes so that very little liquid enters the vent line.
Gases are prevented from flowing back into the pump chamber from the vent line by a nonreturn valve which is arranged behind the membrane in the vent path. During venting, a small amount of liquid always flows through the nonreturn valve into the vent line and back to the intake container. After venting, the nonreturn valve wetted with liquid is surrounded by gas or air, the liquid gradually drying off. Difficulties frequently arise at this stage because the partly dried residues of liquid cause the valve element to adhere firmly to the seat of the nonreturn valve, especially where the liquid has a tendency to crystallize. When it comes to the next venting cycle, the gas pressure on the nonreturn valve is generally not sufficient to open the valve.
Another known feed pump for conveying liquids in dosed amounts is also has a vent and return line to the intake container. However, the venting valve is arranged within the flow path from the pump chamber to the liquid outlet. When the liquid is deaerated, the vent line is closed by a closure element which is connected by supporting arms to a control membrane. Provided between the control membrane and the closure element is a nonreturn valve which is referred to as a “central nonreturn valve”. The vent valve is dependent only upon the pressure acting on the membrane and not upon the aggregate state of the fluid bearing against it. In this known pump, the venting rate is determined by the size of the control membrane.
3.0. Summary of the Invention
An object of the present invention is to significantly reduce the tendency of a pump of the type mentioned above to become inoperative.
In one embodiment of the invention, the membrane is connected to a closure element which is arranged at a distance therefrom, and which closes the vent line when the membrane is deflected. Also, the valve is arranged between the membrane and the closure element.
In contrast to the first known pump, the membrane of the pump according to one embodiment of the invention does not act simultaneously as a closure element, but only as a control element for such an element. The nonreturn valve is arranged in the space between the membrane and the closure element so that its valve element, for example a ball, is always surrounded by liquid when the liquid is dearated and the vent line thus closed. In this manner, the valve element is unable to stick fast to the valve seat, even in the event of prolonged operation of the pump with dearated liquid. The space between the membrane and the closure element remains filled with the liquid until non-dearated liquid is taken in again, the membrane returns to its rest position and the closure element thus opens the vent line so that the gas can escape.
During the suction stroke in the case of deaerated liquid, the membrane moves back into its starting position and the closure element opens the vent line. In this case, however, air or gases is/are prevented from flowing back by the nonreturn valve. The constant movement of the membrane which takes place even with deaerated liquid—in contrast to the first known pump, prevents the membrane from seizing and contributes towards operational reliability.
Since small quantities of liquid flow off through the vent line during venting and during the change in pressure from the suction to the compression stroke, it is of advantage if the vent line returns to the intake container.
The membrane is kept in this starting position by its own bias or alternatively or additionally via a spring. The response threshold of the valve is determined by this force. This threshold is selected so that the membrane is only active in the presence of dearated liquid in the pump chamber.
A particular advantage of the feed pump according to the invention is that venting is particularly rapid because, with non-deaerated liquid, no control force has to be applied to the membrane to open the vent line. All that is needed is the relatively weak control force on the nonreturn valve.
The dependence of the response behavior of the vent valve upon the aggregate state of the liquid bearing against it is preferably achieved by the membrane forming a continuous surface except for a flow-restricting bore. The diameter of this bore is adapted to the liquid and to the biasing of the membrane, so that the bore forms a sufficiently high flow resistance for the liquid and the membrane is activated during the compression stroke. For gas bearing against the vent valve, the flow resistance is too low to lift the membrane off its seat.
REFERENCES:
patent: 4865525 (1989-09-01), Kern
patent: 4951701 (1990-08-01), Boehmer
patent: 4990066 (1991-02-01), Kern
patent: 5492449 (1996-02-01), Hunklinger et al.
patent: 5588809 (1996-12-01), Klein et al.
patent: 5871566 (1999-02-01), Rutz
patent: 457 146 (1968-07-01), None
patent: 42 19 663 (1993-12-01), None
patent: 42 41 030 (1994-06-01), None
patent: 2 177 183 (1987-01-01), None
Hunklinger Herbert
Rutz Klaus
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Leung Philip H.
Murphy Glenn E. J.
Patel Vinod D
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